The present invention relates to an apparatus for successively feeding a sheet from the top of stacks of sheets.
Apparatus which store a lot of filmy sheets made of, e.g., paper metal or plastic and separately feed the stored sheets one by one are generally known. For copying machines, for example, a sheet feeding apparatus is provided to automatically feed original documents stacked on the tray toward the light exposing table so as to automatically copy the original documents one by one. The sheet feeding apparatus includes an oblique sheet table on which documents are stacked, a guide plate for guiding the documents stacked on the sheet table in such a way that the foremost edges of the documents are successively shifted from the top of the stacked documents, and a pair of rotary feeding rollers (or means) which contact the document nearest the rollers or on top of the stacked documents. The pair of feeding rollers feed the documents one by one in such an order that the documents are pulled in between the rollers. When a lot of documents are stacked on the table, however, the foremost edges of the stacked documents located adjacent to the feeding rollers may not be correctly shifted from the top of the stacked documents successively. If so, the document on the top of the stack is brought into contact with one feeding roller at a position where the top document is farther from the contact portions of the paried feeding rollers than some of the successively following document, so that not the top document but a second or third sheet may be pulled in between the contact portions of the paired feeding rollers prior to the top document. Namely, the conventional sheet feeding apparatus has the drawback that the stacked documents could not be successively fed from the top thereof.
In addition when a lot of documents are stacked on the document table, there is the disadvantage that an document other than the top one, and nearest to the feeding rollers may be pulled in between the feeding rollers prior to the top document, when the foremost edge of the top document is curled or when the foremost edges of the documents are not correctly shifted from the top of the stacked documents successively because of the friction between the documents. Accordingly, conventional sheet feeding apparatus are not reliable in successively feeding documents.